INTRODUCTION. 



which, without such check, would, from their undue increase, be- 

 come seriously detrimental. Some catch them on the wing. The 

 Swallows and the Swifts, from early morning till the close of day, 

 ply their untiring pinions in pursuit of such as fly abroad by day- 

 light ; and when evening comes, only give up the chase to kindred 

 species, that prefer the gloom of twilight or the silence of the 

 night. 



is[or do they live on winged insects only ; but in all stages of 

 their growth, the insect hosts are the appointed food of numerous 

 tribes of birds, adapted by their structure to obtain such prey 

 wherever met with : on the ground, beneath the bark of trees, in 

 every hole and crevice where they lurk, their presence is detected. 

 From the upturned soil, thousands of beaks are ready to pick out 

 the wingless grubs ; and prying eyes investigate each leaf of every 

 tree, in search of caterpillars and the hungry bands of similar 

 destroyers. 



Fed on more dainty fare, the Humming-Birds and Soui-mangas, 

 with their slender bills, explore the blossoms of a thousand plants 

 in search of honied stores, sipping the nectar and the dew from 

 flower-bells beauteous as themselves. Some feed on fruits, and 

 in the sunny climes find a perpetual autumn, or devour the seeds 

 of grasses, and, unasked, approach the harvest-field to share the 

 abundant corn. Terrestrial in their habits, not a few scrape from 

 the ground their vegetable food ; while many, raised on stilted 

 legs, wade in the marsh, and probe the oozy soil in search of 

 worms or slugs. Nor are the lakes, the rivers, or the sea without 

 their feathered occupants : legions of water-fowl are everywhere 

 dispersed. Ducks paddle in the ponds, Swans row their " oary 

 state," reflected on the tranquil bosom of the stream ; multitudes 

 frequent the shore, crowding the rocks or riding on the waves ; 

 while far away at sea, upborne on outstretched wings, the Alba- 

 trosses sweep along over degrees of longitude, and circle round 

 the globe itself, in the unbounded freedom of their flight. 



Presenting so much variety in their, occupations and mode of 

 life, it may naturally be supposed that a corresponding diversity 

 exists in the structure of their limbs, and in their means of pro- 

 curing their subsistence. The feet and claws of a perching bird 

 could never be available for swimming, nor could the bill of a 

 Snipe be used for the same purpose as the beak of an Eagle. In 

 the classification of birds, therefore, the ornithologist is guided by 

 certain characters, derived from their general shape and propor- 

 tions, the structure of their mouth, bill, tongue, wings, tail, and 



